Indexing apparatus

ABSTRACT

An indexing apparatus for indexing an article about an axis. The indexing apparatus is adapted to be removably attached to the article and is constructed to axially displace the article along the axis to a disengaged position upon the initial application of a rotary force to an indexing assembly housed within the indexing apparatus. When in the disengaged position, the article can be selectively rotated about the axis by the further application of rotary force to the indexing assembly so that the article may be positioned in a predetermined angular position. The indexing apparatus further includes a device for locking the article in a plurality of predetermined angular positions when the application of rotational force to the indexing assembly is discontinued.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to indexing apparatuses and, moreparticularly, is directed to indexable apparatuses for selectivelyorienting objects such as workholding devices in precise predeterminedpositions.

2. Description of the Invention Background

A number of different apparatuses have been developed for indexing avariety of articles between manufacturing operations to increase theefficiency of the manufacturing process. For example, various types ofindexing apparatuses are typically used to accurately present aworkpiece in a predetermined orientation relative to the spindle of amachining device such as a milling machine or the like.

One type of such indexing device is disclosed in U.S. Pat. No. 2,339,986to Engert. The device in that patent comprises an indexable device forindexing a shaft into a variety of different machining orientationsabout a single axis. While this device advantageously can support ashaft in various orientations to enable, for example, keyways to be cutin different locations on the shaft, the device can only hold a singleshaft at a time and is ill-suited for supporting non-cylindricalworkpieces.

Another indexable device is disclosed in U.S. Pat. No. 3,020,998 toWebb. That device comprises a turntable adapted to be indexed by thecyclic operation of a ratchet and pawl mechanism. A plurality ofvise-like workholders are supported on the table and are adapted to beindexed about an axis such that the workholders can be positioned invarious orientations relative to metal bending or crimping apparatus.This device, however, can only support workpieces in single planarorientations about the device's axis. Moreover, the ratchet and pawlsystem cannot be used to index the workholders to very precise andminute different angular orientations.

U.S. Pat. No. 2,369,425 to Becker discloses an indexable workholdingdevice that comprises a frame that is adapted for attachment to themachining table of a machining device such as drill press. A disk isrotatably attached to the frame and may be rotated about an axis andsecured in a predetermined position by clamping members attached to theframe. The top of the disk is also configured to accept workpieceholding clamps thereon. The outer edge of the disc is provided with avernier scale that cooperates with an indicator on the frame to veryprecisely indicate the rotational position of the disc relative to theframe. The workpiece accuracy is dependent upon the upon the secureclamping of the disk in position and the secure clamping of theworkpiece on the disk. If either the workpiece or the disk moves evenslightly, the workpiece accuracy will be compromised. A similarapparatus for retaining workpieces at selective angles is also disclosedin U.S. Pat. No. 2,406,043 to Sorensen. That device also comprises arotatable plate member that is equipped with a plurality of threadedapertures adapted to receive workholding clamping members therein.Although this device is capable of indexing a workpiece at relativelyprecise angular orientations, if the clamping assemblies attaching theworkpiece move, the workpiece accuracy is compromised.

All of the above indexing apparatuses have limitations. In particular,those apparatuses that can position an item or workpiece in a relativelyaccurate position are generally incapable of supporting the workpiece ina very accurate and rigid position when it has external forces, such asthose typically generated by various machine tools, assembly apparatusesor other manufacturing devices applied thereto. Such indexingapparatuses that do provide an adequate degree of rigidity typicallycannot achieve the desired positioning accuracy or they are expensive tomanufacture and maintain.

A number of indexing apparatuses typically can only index items about avertical or horizontal axis or they can only index items that arereceived or oriented in a common plane. Such indexing apparatuses arenot well suited for use in those applications wherein it is desirable topresent multiple surfaces of multiple workpieces to the spindle of amachining device. It will be appreciated that by indexing a workpiecerelative to the spindle of a machining device, several workpiecesurfaces typically may be machined without the necessity of removing theworkpiece from the workholder and re-clamping it in other machiningorientations.

One device that addresses this problem is manufactured by Chick MachineTool, Inc. of 800 Commonwealth Drive, Warrendale, Pa. 15086 under thetrademark "Multi-Lok". This devise comprises a vise-like clampingassembly that is equipped with first and second movable jaw supports towhich first and second jaw members may be removably attached. A fixedcenter jaw is attached between the movable jaws to provide two workpieceholding stations. Multiple two-station clamping assemblies can bereceived on a common column member that has a plurality of slidereceiving slots therein. A column supporting base plate can beselectively attached to end of the column to enable the column to beattached to an indexable workholding table and thus enable the column tobe selectively rotated relative to the spindle of, for example, ahorizontal CNC milling machine. Such device, however, relies on anindexing mechanism that is a part of the milling machine. As such, itcannot be used to index workpieces on other machining devices that arenot equipped with such indexable support members.

Another multiple workholding device manufactured by Chick Machine Tool,Inc., under the trademark "Multi-Dex", is also well-suited for clampingand selectively indexing a plurality of workpieces within the machiningenvelope of a machining device. This workholding device, in general,comprises a column member that supports a plurality of vise-likeclamping assemblies that are similar to the Multi-Lok assembliesdescribed above. However, the column member has a base plate formedthereon or attached thereto that may be attached to a selectivelyindexable support apparatus. Examples of selectively indexable supportsare disclosed in U.S. Pat. No. 4,991,463 and U.S. Pat. No. 4,884,474both to Kawata. Such assembly can be automatically indexed without theaid of hydraulic or electrical power, simply by contacting an actuatormember with the machining device's spindle or the machine tool that isattached thereto. When a single two-station workholding device isindexed, the two workpieces retained therein can be machined on threesides before they must be removed from the workholder. Because theworkholders described immediately above provide means for indexing fourtwo-station workholders, a total of twenty four machining sequences (twoworkpieces/workholder×three sides/workpiece yields six exposed sides formachining sequences×four workholders) can be performed before theworkpieces have to be removed from the workholders to be reoriented ifnecessary. Such device therefore increases the machine operator's "walkaway" time (i.e., the time the machine can advance through preprogrammedmachining sequences without the aid of an operator to relocate orreposition the workpiece(s)) and, thus, increases the machiningapparatus' efficiency. However, this device is adapted to be actuated bythe machining apparatus itself and, thus, is not well adapted for manualactuation. Moreover, due to the types of gears used to lock theworkholder in various angular positions, very precise accuracies of, forexample, three arc seconds, cannot be achieved.

Thus, there is a need for an apparatus capable of indexing one or moreitems to very precise orientations about an axis that can also rigidlyretain such items in that orientation when the items are under theinfluence of external forces.

There is a further need for an indexing apparatus that has theabove-mentioned attributes that is relatively inexpensive to manufactureand maintain.

There is yet another need for an indexing apparatus that can be can beeasily adapted to index items about a horizontal or a vertical axis.

There is a need for an indexable workholding apparatus that canselectively support a plurality of workpieces or workholders in veryaccurate angular orientations.

There is a further need for an indexable apparatus that can be easilyused in connection with a variety of different machining apparatuses.

SUMMARY OF THE INVENTION

In accordance with a particular preferred form of the present invention,there is provided an apparatus for selectively indexing an article aboutan axis. The apparatus, in a preferred form, comprises a housing memberand an indexing assembly that is attached to the housing member and thearticle. The indexing assembly is constructed to selectively axiallydisplace the article along the axis to a disengaged position when arotary force is initially applied thereto and permits the article tothereafter be selectively rotated to a predetermined angular positionabout the axis upon the further application of rotary force to theindexing assembly. The indexing assembly is further adapted toselectively retain the article in a predetermined angular position whenthe further application of rotary force is discontinued.

In another embodiment of the present invention, an indexable workholdingapparatus is disclosed. In a preferred form, the indexable workholdingapparatus comprises a longitudinal column member that has a firstlongitudinal axis and operably supports at least two pairs ofselectively movable jaw members for selectively clamping workpiecestherebetween. Each pair of jaw members is selectively movable alongslots in corresponding second longitudinal axes that are substantiallyparallel to the first longitudinal axis. First and second supportmembers are provided for rotatably and axially supporting thelongitudinal column therebetween for selective axial and rotationalmovement relative to the first longitudinal axis. The apparatus furthercomprises an indexing assembly that is attached to the second supportmember and communicates with the longitudinal column member. Theindexing assembly is adapted to selectively axially displace the columnmember along the first longitudinal axis to a disengaged position when arotary force is applied to the column member to thereby permit thecolumn member to thereafter be selectively rotated to a predeterminedangular position about the first longitudinal axis upon the furtherapplication of rotary force thereto and selectively retain the columnmember in the predetermined angular position when the application ofrotary force is discontinued.

Thus, it is an object of the present invention to provide an indexableapparatus that can be used to index a variety of different articlesabout an axis to very precise angular orientations.

It is another object of the present invention to provide an indexableapparatus with the above-mentioned attributes that can rigidly retainthe article(s) attached thereto in the predetermined angularorientation(s).

It is yet another object of the present invention to provide anindexable workholding apparatus that can selectively support a pluralityof workpieces within the machining envelope of a machining device atvery precise angular orientations.

It is a further object of the invention to provide an indexableworkholding apparatus that can be easily manually indexed to veryprecise angular orientations.

It is yet another object to provide a device that can be easilytransported and used in connection with a variety of different machiningdevices.

Accordingly, the present invention addresses the foregoing problemsassociated with other indexable apparatuses. The present invention alsoenables a plurality of workpieces to be selectively indexed to andfirmly retained in very precise angular orientations relative to thespindle of a machining apparatus. Thus, the present invention serves tofurther maximize the use of the machining envelope and thereby minimizesthe amount of machine downtime encountered when using other devices. Thesubject invention can be easily actuated by the manual application offorce thereto and thus does not require the machine tool device toprovide the actuation force. In addition to those advantages, otherdetails, objects, and advantages will become apparent as the followingdetailed description of the present preferred embodiments hereofproceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, there is shown present preferredembodiments of the invention wherein like reference numerals areemployed to designate like parts and wherein:

FIG. 1 is top cross-sectional view of a preferred indexable device ofthe subject invention with the indexing assembly thereof in an engagedposition, with some of the elements thereof shown in full view forclarity;

FIG. 2 is another cross-sectional view of the indexable device of FIG. 1with the indexing assembly thereof in a disengaged position, with someof the elements thereof shown in full view for clarity;

FIG. 3 is an isometric view of a preferred indexable device of thepresent invention supporting a preferred workholding assembly on anapertured grid plate;

FIG. 4 is side elevational view of the indexable workholding assembly ofFIG. 3;

FIG. 5 is an end elevational view of the front end of the indexableworkholding assembly of FIG. 4;

FIG. 6 is an end elevational view of the opposite end of the indexableworkholding assembly of FIGS. 4 and 5;

FIG. 7 is a partial cross-sectional side elevational view of a columnmember of an indexable workholding assembly, with some of the elementsthereof shown in full view for clarity;

FIG. 8 is an end elevational view of the column of FIG. 6 with some ofthe elements thereof in cross-section;

FIG. 9 is a partial cross-sectional assembly view of a column receivedon a preferred front support member of an indexable workholdingapparatus of the present invention showing some of the elements thereofin full view for clarity; and

FIG. 10 is a partial cross-sectional assembly view of a column receivedon a preferred rear support member, with some of the elements thereofshown in full view for clarity.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings for the purposes of illustrating presentpreferred embodiments of the invention only and not for purposes oflimiting the same, FIGS. 1 and 2 illustrate a preferred indexableapparatus 10 that has a housing 11 that can be operably attached tovariety of different support structures (not shown) to orient thedevice's axis of rotation "A--A" in a desired orientation. As thepresent Detailed Description of Preferred Embodiments proceeds, thereader will appreciate that the present indexable device 10 may be usedin a variety of different applications wherein it is desirable to indexan item or a plurality of items about an axis at preferred incrementsof, for example, 5° at a very high accuracy of, for example,approximately ±three arc-seconds.

More particularly and with reference to FIGS. 1 and 2, the presentindexing apparatus 10, in a preferred form, includes an indexingcoupling 20 commonly known in the art as a "Curvic-type" or "Hirth-type"coupling. The indexing coupling 20 comprises a first indexing or toothedring 22 and a second indexing or toothed ring 70 adapted for meshingengagement with the first toothed ring 22. As can be seen in FIGS. 1 and2, an object 15 that is to be indexed is non-rotatably attached to thesecond toothed ring 70 preferably by cap screws 17 that are received inthreaded bores 71 in the second toothed ring 70. The skilled artisanwill appreciate that object 15 can comprise a variety of different itemssuch as, for example, workholders for holding one or more workpiecestherein. It will be further appreciated that the object 15 may beattached to the second toothed ring 70 by other suitable methods withoutdeparting from the spirit and scope of the present invention.

The first toothed ring 22 is attached to the housing 11, preferably bycap screws 24 and has two bores (26, 27) therein that are coaxiallyaligned on axis "A--A". Coaxially received within the bores (26, 27) isa displacement assembly, generally designated as 28. The displacementassembly 28 comprises, among other things, a ball screw assembly 30, aball screw support ring 40 and a retaining plate assembly 60. Theconstruction and operation of the ball screw assembly 30 is well knownin the art and, therefore, will not be discussed in great detail herein.In general, however, the ball screw assembly 30 comprises a screw member32 that is rotatably housed within a ball nut 34. The ball nut 34 andthe screw member 32 have helical grooves therein that cooperate to formhelical passages, generally designated as 36, that house a plurality ofball bearings 38 therein. Rotation of the screw member 32 will cause itto be axially advanced relative to the ball nut 34. In addition, screwmember 32 has a radially extending engagement pin 33 attached theretothat, as will be discussed in further detail below, is designed to limitthe rotation of the screw member 32 to an angular path of approximately270° about axis "A--A".

The ball screw assembly 30 is supported within a bore 14 provided withinthe housing that is coaxially aligned on axis "A--A" by the ball screwsupport ring 40. In particular, as shown in FIGS. 1 and 2, the ballscrew support ring 40 has a first hub portion 42 and a second hubportion 46. The first hub portion 42 has a first coaxial bore 48 thereinthat is sized to slidably and rotatably receive the screw member 32 andthe second hub portion 46 has a second coaxial bore 50 that is sized toreceive the ball nut 34. Ball nut 34 is non-rotatably attached to theball screw support ring preferably by pin 52. To prevent chips and otherdebris from becoming lodged between the first hub portion 42 and thescrew member 32, a groove 43 is provided in the first hub portion 42 forreceiving a commercially available resilient wiper member 44 therein.

As can also be seen in FIGS. 1 and 2, a retaining plate assembly 60 isreceived on the ball nut 34. In particular, the retaining plate assembly60 has a bore 62 therethrough that is adapted to receive a portion ofthe ball nut 34 therein. A plurality of capscrews 64 serve to attach theretaining plate assembly 60 to the ball screw support ring 40. Also in apreferred embodiment, the second toothed ring 70 of the indexingcoupling 20 has a bore 72 therethrough and is adapted to be coaxiallyreceived on the first hub portion 42 of the ball screw support ring 40such that the teeth thereof are in a confronting intermeshingorientation with the teeth of the first toothed ring 22. To preventchips and debris from entering between the bore 72 of the second toothedring 70 and the first hub portion 42 of the ball screw support ring 40,a groove 54 is provided around the perimeter of the first hub portion 42for housing an O-ring 56 therein.

The first and second toothed rings (22, 70) are preferably biased intomeshing engagement by a plurality of Belleville washers 76 that arereceived on the second hub portion 46 as shown in FIGS. 1 and 2.Preferably three Belleville washers 76, sized to create a meshing forceof approximately 2000 pounds, are coaxially received with a thrustwasher 78 in bore 27 of the first toothed ring 22. As can also be seenin FIGS. 1 and 2, a bearing member 80 is received on the second hubportion 46 of the ball screw support ring 40 between the retaining plateassembly 60 and the thrust washer 78 to provide rotational support tothe thrust washer 78 and, ultimately, to the displacement assembly 28.

As shown in FIGS. 1 and 2, the screw member 32 may be advantageouslyprovided with a hexagonal shaped protrusion 35 that is sized to receivea hexagonal shaped cavity 117 of an actuator shaft 19 that is rotatablysupported within the object 15 by known means. As the presentDescription proceeds, the skilled artisan will appreciate that thepresent indexing device 10 may be easily manually actuated by rotatingthe actuator shaft 19 in a clockwise direction, thus rotating the ballscrew member 32. However, ball screw member 32 may be selectivelyrotated by a number of automated devices (i.e. motors, etc.) andtherefore, the scope of protection afforded to the claims appendedhereto should not be limited by the source of actuation power that isapplied to the ball screw member 32.

Also in a preferred embodiment, to provide an indication of the angularposition of column 50 about axis "A--A", an angular scale member 74 isattached to the perimeter of the second toothed ring 70 such that ittravels therewith. The scale member 74 is also provided with an annularportion 75 that is adapted to be selectively received within an annularspace 77 between the inner surface of cavity 12 and the outer perimeterof the first toothed ring 22. In addition, one or more angularindicators 79 are attached to the housing 11 and cooperate with thescale member 74 to provide the operator with a visual indication of theangular position of the second toothed ring 70 and, ultimately, theobject 15.

Preferably received within an annular groove 81 in the housing 11 is acommercially available wiper member 83. A second wiper member 87 ispreferably received in annular groove 85 in the perimeter of the firsttoothed ring 22. As will be discussed in further detail below, wipers(83, 87) serve a two-fold purpose; namely, to prevent chips and debrisfrom entering into the cavity 77 and to provide a sufficient amount offrictional force to retain the second toothed ring 70 in a momentary"disengaged" position as the ball screw member 32 is being rotatedthrough the final portion of its radial path.

In particular, the operation of the indexable device 10 is, essentially,a two step process and can be understood from further reference to FIGS.1 and 2. FIG. 1 illustrates the displacement assembly 28 in an "engaged"position wherein the first and second toothed rings (22, 70) are biasedinto meshing engagement by the force created by the Belleville springs76. Thus, to index the object 15, the second toothed ring 70 must firstbe axially advanced out of meshing engagement with the first toothedring 22. To accomplish that task, a rotational actuation force isinitially applied to the actuator shaft 19 to cause it to rotate in aclockwise direction about axis "A--A". The initial rotation of the shaft19 in a clockwise direction causes the ball screw member 32 to alsorotate in a clockwise direction. The screw member 32 is rotated througha preferred 270° path of rotation that is limited by the engagement ofthe engagement pin 33 with a portion of the first hub member 40. Becausethe axial motion of the ball screw member 32 is restrained in the "B"direction by the housing 11, such rotation of the ball screw member 32causes the ball nut 34 to axially advance in the "C" direction, thusdisengaging the second toothed ring 70. In a preferred embodiment, theball screw assembly 30 is so arranged such that, just prior to theengagement of the engagement pin 33 with the first hub portion 40 (i.e.,when the screw member 32 has rotated through a path of approximately250°), the screw member 32 will have axially advanced the ball nut 34 ina "C" direction against the force generated by the Belleville springs 76to thereby cause the first and second toothed rings (20, 70) to bedisengaged. See FIG. 2. It will be appreciated that the ball screwassembly 30 is sized to provide the requisite mechanical advantage tosufficiently compress the Belleville springs 76 to permit the secondtoothed ring 70 to be biased out of meshing engagement. As was mentionedabove, in a preferred embodiment, the Belleville springs 76 arepreferably sized to provide approximately 2000 pounds of meshing forceto the first and second toothed rings (22, 70). However, the Bellevillesprings 76 and the ball screw assembly 30 may be appropriately sized toprovide any other suitable meshing force.

In a preferred embodiment, the wipers (83, 87) are sized and sopositioned relative to the annular portion 75 of the scale 74 to createan amount of frictional rotational forces therebetween (i.e.,approximately 10 ft-pounds) that is somewhat greater than the rotationalforce required to operate the ball screw member 32. The frictionalforces serve to overcome the forces required to operate the ball screwmember 32 including the forces created by the Belleville springs whichwould otherwise cause the second toothed ring member 70 to axially movein the "B" direction and possibly contact the first toothed ring 22while the screw member 32 is further rotated through the final portionof its preferred 270° radial path (i.e., until the engagement pin 33engages the first hub 40). When the engagement pin 33 engages the firsthub 40, it causes the displacement assembly 28 to be selectively rotatedon the bearing 80 and thereby, by virtue of its connection to the secondtoothed ring 70, causes the second toothed ring 70 and, ultimately, theobject 15 to be rotated about the axis "A--A". It will be understoodthat while the frictional rotational force generated by the wipers (83,87) is sufficient to overcome the rotational force required to operatethe ball screw 32, such frictional force may be easily overcome by thefurther manual application of rotary force on the ball screw member 32.The skilled artisan will recognize, however, that other mechanisms maybe used to provide the requisite frictional force without departing fromthe spirit and scope of the present invention. After the object 15 hasbeen rotated to a desired position, the shaft 19 is slowly permitted toturn in a counterclockwise direction under the biasing force of theBelleville springs 76 which causes the second toothed ring 70 tore-engage the first toothed ring 22 and thus, rigidly retain the object15 in that position.

In a preferred embodiment, a cavity 14 in the housing member 11 isprovided with engagement notches 16 therein preferably arranged at 90°intervals, however, any number of engagement notches 16 may be providedin the inner wall of the cavity 14. The engagement notches 16 areadapted to receive therein one or more spring-biased detent pins 90 thatare received within the retaining plate assembly 60. More particularly,one or more radial bores 66 are provided in the outer perimeter of theretaining plate assembly 60 and are sized to slidably receive therein acorresponding detent pin 90. Preferably, each detent pin 90 has anoversized transverse bore 92 therethrough that is adapted to receive atransverse pin member 68 attached to the retaining plate assembly 60 asshown in FIGS. 1 and 2. The reader will appreciate that the transversepin 68 serves to movably retain the detent pin 90 within the radial bore66. A coil spring 94 is provided between the detent pin 90 and thebottom of the bore 66 to bias the detent pin 90 in an outward radialdirection to engage an engagement notch 16 in the housing 11. It will beappreciated that when the end of the detent pin 90 is received withinone of the notches 16, the indexing assembly 28 is further locked inthat radial position. Preferably, the end of the detent pin 90 issubstantially rounded such that it can be biased out of engagement witha notch 16 when the indexing assembly 28 is rotatably actuated.

As can be seen in FIGS. 3-9, the indexing device 10 of the presentinvention can also be most advantageously used in connection with aworkholding column member 150 to create a selectively indexableworkholding assembly 200 that can be attached to a grid plate 130 in aprecise position for supporting a plurality of workpieces in variousmachining orientations relative to a machining device (not shown). Itwill be further appreciated that such grid plate 130 is adapted to befastened to the milling table (not shown) of a machining apparatus suchas a milling machine (not shown) by known fastening and locating means.

More particularly and with reference to FIG. 3, the workholding assemblypreferably comprises a column member 150 that is rotatably supported byan indexable support apparatus, collectively designated as 210, thatcomprises, among other things, a "first" upstanding support member 220and a "second" upstanding support member 300 that houses an indexabledevice 10 of the present invention therein. The column 150 depicted inthe present Figures comprises an elongated metallic structure typicallyfabricated from a high strength aluminum material having fourlongitudinal surfaces 152 thereon. The skilled artisan will readilyappreciate, however, the indexable support assembly 210 of the presentinvention can be used to support columns of various other shapes andconstructions without departing from the spirit and scope of the presentinvention.

As can be seen in FIGS. 3, 9, and 10 the column 150 has a longitudinalaxis "D--D" about which it can be selectively rotated. A longitudinallyextending cavity 154 having a longitudinal axis "E--E" is preferablyprovided in each surface 152 of the column 150 such that each axis"E--E" is substantially parallel to axis "D--D". See FIG. 4. Eachlongitudinal cavity 154 defines a corresponding slot 156 having twolongitudinally extending side rail members 157. See FIG. 8. In addition,a corresponding clamping assembly, generally designated as 160, isprovided for longitudinal movement within each cavity 154. The clampingassemblies 160 are preferably of the type disclosed in U.S. Pat. No.5,024,427, the disclosure of which is herein incorporated by reference.In addition, in this embodiment, the clamping assemblies 160 arepreferably identical in construction. As such, a single clampingassembly will be herein described with it being understood that all ofclamping assemblies 160 are of identical construction.

In general, a clamping assembly 160 preferably comprises a first movablesupport member 162 and a second movable support member 168 which areeach adapted to be received within a corresponding slot 156 in thecolumn 150. See FIG. 7. The clamping assembly 160 also preferablyincludes a screw shaft 174 that is sized to be received within acorresponding slot 156 in the column member 150. The screw shaft 174preferably has threads 176 which are intended to engage a threaded bore163 within the first movable support member 162. In addition, the screwshaft 174 includes means (not shown) for engaging and displacing thesecond movable support member 168 thereon. The screw shaft 174 passesthrough the second movable support member 168 while the other end of thescrew shaft 174 is configured to receive an allen wrench or otherapparatus for selectively supplying rotary motion to the screw shafts174 received within the cavities 154 of the column 150.

A "first" center jaw 158 is preferably attached to each surface 152intermediate the column ends in a predetermined position. In a preferredembodiment, each center jaw 158 is removably attached to itscorresponding surface 152 by cap screws 159 that extend throughcorresponding bores 161 in the center jaw member 158. Preferably,locating bushings 175 are pressed into corresponding bores in eachsurface 52 and are coaxially arranged with threaded bores (not shown) inthe column 150. One locating bushing 175 preferably has a round aperturetherethrough and the other locating bushing 175 preferably has anelongated "slot" therethrough. The bushings 175 are adapted to receivetherein the shoulder portions of corresponding capscrews 159 toprecisely locate the center jaw 158 on the surface 152. Other locatingpin arrangements that are known in the art may also be used to preciselylocate each center jaw member 158 on a corresponding surface 152 of thecolumn 150. For example, the locating arrangement such as the onedisclosed in a copending U.S. patent application entitled "Apparatus ForPositioning An Element On A Surface", Ser. No. 08/300,375, filed Sep. 2,1994, owned by the owner of the present application, the disclosure ofwhich is herein incorporated by reference, may also be used in thoseinstances wherein it is desirable to have each center jaw 158 preciselylocated on and attached to each surface 152 of column 150.

As shown in FIG. 7, a "first" jaw member 180 corresponds with each firstmovable support member 162 and is preferably removably attached thereto.Similarly, a second jaw member 186 corresponds with each second movablesupport member 168 and is removably attached thereto. The jaw members(180, 186) are preferably similar to those workholding jaw portionsdisclosed in U.S. Pat. No. 5,025,427 entitled "Quick Change Head ForPrecision Machine Vise" the disclosure of which is also hereinincorporated by reference. As such, in the present "Detailed DescriptionOf Preferred Embodiments", the basic jaw structure of each clampingassembly 160 will be described in general terms, it being understoodthat the particular details of the jaw member construction, with theexception of those features which are described hereinbelow formingthese embodiments of the present invention, may be gleaned from a reviewof that patent.

In general, as can also be seen in FIG. 7, each first movable supportmember 162 has a "first" extended portion 164 that extends above thecorresponding surface 152. The first extended portion 164 has a "first"transverse bore 165 extending therethrough that has a "first" flatsurface 166 machined therein. Similarly, each second movable supportmember 168 has a "second" extended portion 170 that extends above thecorresponding surface 152. The second extended portion 170 has a"second" transverse bore 172 that extends therethrough that has a"second" flat surface 173 machined thereon. In addition, each first jawmember 180 preferably has a "first" cavity 182 therein that is sized toreceive a "first" extended portion 164 of a corresponding first movablesupport member 162. A "primary" transverse bore 184 is preferablyprovided through the first jaw member 180 such that the primarytransverse bore 184 will be substantially coaxially aligned with thefirst transverse bore 165 when the first extended portion 164 isreceived within the first cavity 182 in the first jaw 180. See FIG. 7.Also, each second jaw member 186 preferably has a "second" cavity 187therein that is sized to receive a second extended portion 170 of acorresponding second movable support member 168. Also, a "secondary"transverse bore 188 is preferably provided through the second jaw member186 such that the secondary transverse bore 188 will be substantiallycoaxially aligned with the second transverse bore 172 when the secondextended portion 170 is received within the second cavity 187 in thesecond jaw member 186.

The first jaw members 180 are preferably removably attached to theircorresponding first movable support members 162 and the second jawmembers 186 are preferably removably attached to their correspondingsecond movable support members by removable pins 190. The preferredconstruction of pins 190 is set forth in detail in U.S. Pat. No.5,024,427, the disclosure of which was incorporated by referencehereinabove. In general terms, however, each pin 190 has a planarportion 192 which is adapted to be brought into contact with the flatsurfaces (166, 173) in bores (165, 172). In particular, each first jaw180 is preferably removably attached to a corresponding first movablesupport member 162 by inserting a corresponding pin 190 through thecoaxially aligned bores 184 and 165 such that the planar portion 192 ofthe pin 190 engages the first flat surface 166 of the first transversebore 165. Similarly, each second jaw 186 is preferably removablyattached to a corresponding second movable support member 168 byinserting a corresponding pin 190 through the coaxially aligned bores188 and 172 such that the planar portion 192 of the pin 190 engages thesecond flat surface 173 of the second transverse bore 172.

As can be seen in FIG. 7, each center jaw 158 is arranged on acorresponding surface 152 of the column 150 such that the correspondingfirst and second movable support members (162, 168) may move toward andaway from the corresponding center jaw member 158 to cause, for example,workpieces 153 and 155 to be clamped between the center jaw 158 andfirst and second jaws (180, 186). For example, when a screw shaft 174 isrotated, the first movable support member 162 is moved relative to thecenter jaw 158, thereby causing the first jaw 180 to move toward thecenter jaw 158 to clamp a first workpiece 153 therebetween. In addition,the rotation of the screw shaft 174 and its movement relative to thefirst movable support member 162 causes the second movable supportmember 168 to move toward the center jaw member 158 to cause the secondjaw member 186 to engage and restrain a second workpiece 155 between thesecond jaw member 186 and the center jaw member 158.

Also, a debris shield 350, is preferably positioned between the surfaceand the corresponding first and second jaw members (180, 186) to preventchips and debris from entering the longitudinal cavities 154.Preferably, the debris shield 350 has a first opening 352 thereinadapted to receive a corresponding first extended portion 164 and asecond opening 354 therein adapted to receive a corresponding secondextended member 168. In addition, debris shield 350 has bores 356adapted to receive bushings 175 therein. Debris shield 350 is preferablyfabricated out of tool steel having a Rockwell hardness of approximately50 (C scale). It will be appreciated that when the debris shield 350 isreceived on a corresponding surface 152 as shown in FIG. 7, the clampingassembly 160 is longitudinally retained within its corresponding cavity154 by virtue of the debris shield's engagement with the bushings 175 incooperation with the openings (352, 354) in the debris shield 350. Itwill be appreciated that openings (352, 354) are sized relative to thefirst and second jaw members (180, 186) such that regardless of wherethe first and second jaw members (180, 186) are located, the openings(352, 354) are always covered to prevent any debris from entering thelongitudinal cavity 154.

As mentioned above, the column member 150 is rotatably supported on anindexable support assembly 210 that comprises a first upstanding supportmember 220 and a second upstanding support member 300 that areattachable to a grid plate 130. The first support member 220 ispreferably fabricated from aluminum in the shape shown in FIGS. 3 and 9.However, the reader will appreciate that the first support member 220can be fabricated from other suitable materials in various other shapes.Preferably, the first support member 220 has a lower support plate 222attached thereto that is designed to support the first support member220 on a grid plate 130 that has a plurality of bores 132 thereinarranged in a predetermined array of orthogonally arranged rows andcolumns. "Tooling" or "grid" plates of this type are known in the artand, therefore, will not be discussed in great detail herein. However,in this embodiment, each bore 132 in the grid plate 130 preferably has alower threaded portion 134 and a locating bushing 136 pressed thereinthat is fabricated from hardened tool steel. See FIG. 7. As can be seenin FIG. 5, the opposing lower ends (226, 228) of the first supportmember 220 are each preferably provided with a fastener cavity 230. Eachfastener cavity 230 has a fastener bore 232 therein that is coaxiallyaligned with a corresponding very accurately sized bore 232 in thesupport plate 222. See FIG. 9. Preferably, a locating screw 234 having avery accurately ground locating shoulder is inserted through thefastener bores (232, 233) to be threadedly received in correspondingthreaded bores 134 in the grid plate 130. It will be appreciated thatthe shoulder portion of the screw 234, in cooperation with the bushing136, serves to accurately locate the first support member 220 on thegrid plate 130. Such locating and fastening method advantageouslypermits the workholding assembly 200 to be slidably positioned on thegrid plate 130 during the initial orientation thereof. Furthermore,those of ordinary skill in the art will appreciate that by locating thelocating screws 234 inside of the first support member 220, thefasteners and the support member are less susceptible to damage thanother prior designs. This method of locating and attaching the firstsupport member 220 to the grid plate 130 is also preferably used toattach the second support member 300 to the grid plate 130. The skilledartisan will further appreciate, however, that the first and secondsupport members (220, 300) can be attached to a grid plate or othermember in precise relationship to one another by a myriad of other knownlocating and fastening methods and apparatus without departing from thespirit and scope of the present invention. For example, the apparatusdisclosed in the copending U.S. patent application entitled "Apparatusfor Positioning An Element On A Surface", Ser. No. 08/300,375, that wasmentioned above and herein incorporated by reference may also besuccessfully used to attach the first and second support members (220,230) of the present invention to a grid plate 130 in predeterminedorientations.

To prevent chips and debris from entering fastener cavities 230, whileproviding a means for accessing the capscrews 234, slidable chip covers(231, 233) are slidably and overlappingly received in correspondingreceiving slots (223, 225). To gain access to the capscrews 234, thechip covers (231, 233) are simply slidably displaced within the grooves(223, 225).

As can be seen in FIG. 9, a support shaft 240 is rotatably receivedwithin an axial bore 242 in the "front" end 151 of column 150 and isrotatably attached thereto by a shaft bushing 244. Shaft bushing 244 ispreferably fabricated from bronze and is adapted to be non-rotatablyreceived within a cavity 241 in the front end 151 of column 150.Preferably, shaft bushing 244 is rigidly attached to column 150 by aplurality of (preferably four) capscrews 245 and has an axial shaftreceiving bore 246 in which shaft 240 is rotatably supported. To preventdebris from infiltrating between the shaft 240 and the shaft bushing244, shaft 240 is preferably provided with an annular groove 250 adaptedto receive therein a commercially available resilient wiper member 252.

Shaft bushing 244 is also adapted to be rotatably received within acorresponding bore 254 provided in the upper portion of first supportmember 220. As can be seen in FIG. 9, the end of shaft 240 is preferablyprovided with a hexagonally shaped cavity 258 to receive a standardallen wrench or other tool to provide rotation to shaft 240 andultimately to the ball screw shaft 32 to thereby cause column 150 torotate about longitudinal axis "D--D". To prevent chips and debris fromentering bore 254, an annular groove 255 is provided in the firstsupport member 220 to retain a resilient endcap member 264 as shown inFIG. 9. End cap member 264 is preferably fabricated from rubber orsimilar material and has an access slit 266 therein through which anallen wrench or other suitable tool may be inserted. See FIG. 5. Also,to prevent chips and debris from entering the cavities 154 in the column150, a plurality of end plate segments 142 are attached to the front end151 of column 150 by capscrews 144 in the manner depicted in FIG. 8.Each end plate segment 142, preferably has an axial bore therethrough(not shown) that provides operational access to the end of thecorresponding screw shaft 174. An endcap member 264 is also preferablyattached to each end plate segment 142 to prevent chips and debris fromaccumulating in those axial bores. In a preferred embodiment, all butone of the endcap members 264 that are attached to the endplates 142 aresimilarly colored. It will be appreciated that the "odd" colored endcap164 indicates a "starting" or reference position to enable the operatorto track the rotational position of the column member 150. Also, tofurther prevent chip and debris infiltration between the shaft bearing244 and the bore 254 in the first support member 220, a resilient gasketmember 268, preferably fabricated from foam rubber or similar material,is provided around shaft bearing 244 as shown in FIG. 9.

The other end of the shaft 240 protrudes from the opposite end 151' ofthe column 150 and preferably has a hexagonal wrench portion 270 formedthereon. A cavity 272 is provided in column end 151' such that it issubstantially coaxially aligned with the shaft 240 along axis "D--D". Analignment ring 274 is coaxially aligned within cavity 272 as shown inFIG. 10. Preferably, alignment ring 274 is retained within the cavity272 by corresponding capscrews 276 and is adapted to assist in thealignment and engagement of wrench portion 270 with the ball screwmember 32' as will be discussed below.

The second upstanding support member 300 is preferably fabricated fromaluminum and is essentially the same as the housing 11 discussedhereinabove and houses a preferred indexable device 10' of the presentinvention that is identical in construction and operation to theindexable device 10 discussed in detail above, except for the followingnoted preferred differences. In particular, the end of the ball screwmember 32' is formed with a hexagonal shaped cavity 310 that is adaptedto receive therein the hexagonally shaped end 270 of the shaft 240. Itwill be appreciated that the second upstanding support member is alsopreferably located on and attached to the grid plate 130 in the mannerdiscussed above. The column member 150 is attached to the second toothedring 70' by a plurality of (preferably four) elongated screw members 322that pass through bores 320 in the column 150 to be threadedly receivedin corresponding threaded bores 71' in the second toothed ring 70'.

To index the column 150 about the longitudinal axis "D--D", a wrench orother suitable tool is inserted into hexagonal cavity 258 in the one endof shaft 240 and the shaft 240 is thereafter rotated clockwise to causethe second toothed gear to be axially displaced along axis "D--D" underthe initial application of rotary force to the ball screw assembly 30'.Thereafter, the further application of rotary force to the ball screwassembly 30' causes the column 150 to be rotated to a desired radialposition. The reader will appreciate that the indexing apparatusoperates in the manner discussed above to selectively index the column150 to a desired orientation. The reader will further appreciate thatthe rotational force required to index the column 150 may be provided bya number of other sources such as electric motors, hydraulic motors,etc. After the column 150 is indexed to the desired position, the rotaryforce is discontinued, permitting the toothed rings (22', 70') tore-engage under the axial force created by the Belleville springs 76'.

The above-disclosed indexable workholding assembly is just one of manyapplications in which the indexable device of the present invention canbe advantageously used. The present indexable device can be used innumerous applications wherein an item or a collection of items must bevery precisely indexed to positions about an axis and retained in thosepositions even under the influence of substantial external forces. Thepresent indexable device is relatively compact and can be incorporatedinto various other support structures as desired. In addition, whencompared to a number of other indexable apparatuses, the presentindexable device is relatively inexpensive and easy to operate.Moreover, the present indexable apparatus can generate very highretaining forces while maintaining the ability to be indexed by themanual application of rotary actuation force thereto. Also, the presentinvention provides solutions to the aforementioned problems associatedwith indexable vise-like workholding apparatuses. While such advantagesare apparent from the foregoing disclosure, it will be understood,however, that various changes in the details, materials and arrangementsof parts which have been herein described and illustrated in order toexplain the nature of the invention may be made by those skilled in theart within the principle and scope of the invention as expressed in theappended claims.

What is claimed is:
 1. Apparatus for selectively indexing an articleabout an axis, comprising:a housing member; and an indexing assemblyattached to said housing member and said article, said indexing assemblyhaving indexing means for selectively axially displacing said articlealong said axis to a disengaged position when a rotary force isinitially applied thereto and permitting said article to thereafter beselectively rotated to a predetermined angular position about said axisupon the further application of said rotary force to said indexingassembly and selectively retaining said article in said predeterminedangular position when said further application of rotary force isdiscontinued.
 2. The apparatus of claim 1 wherein said indexing assemblycomprises:a first toothed ring non-rotatably attached to said housingmember; a second toothed ring axially and rotatably supported by saidhousing member and arranged in confronting relationship with said firsttoothed ring for selective meshing engagement therewith, said secondtoothed ring being attached to said article; and displacement meanssupported by said housing member and communicating with a source ofrotary force, said displacement means selectively axially displacingsaid second toothed ring out of intermeshing engagement with said firsttoothed ring in response to said initial application of rotary force,and permitting said second toothed ring to intermesh with said firsttoothed ring when said rotary force is discontinued.
 3. The apparatus ofclaim 2 wherein said displacement means further comprises:a ball screwassembly axially supported by said housing member along said axis forselectively axially displacing said second toothed ring out ofintermeshing engagement with said first toothed ring in response to saidrotary force; means for removably attaching said source of rotary forceto said ball screw assembly; and biasing means supported by said housingmember for selectively biasing said second toothed ring into saidintermeshing engagement with said first toothed ring when said rotaryforce is discontinued.
 4. The apparatus of claim 3 wherein said biasingmeans comprises at least one spring washer coaxially received on saidball screw assembly for applying an axial force between said first andsecond toothed rings.
 5. The apparatus of claim 4 further comprisingmeans for retaining said second toothed ring in said disengagedorientation after said initial application of rotary force and prior tothe further application of said rotary force to said ball screwassembly.
 6. The apparatus of claim 5 wherein said means for retainingcomprises:an axial annular cavity in said housing member; an annularring member attached to the perimeter of said second toothed ring andarranged for axial travel within said axial annular cavity in responseto said axial displacement of said second toothed ring; and at least onewiper member attached to said housing member and extending into saidaxial annular cavity for engagement with said annular ring member tocreate a frictional force therebetween to retain said second toothedring in said disengaged orientation after said initial application ofrotary force and prior to the further application of said rotary forceto said ball screw assembly.
 7. The apparatus of claim 6 furthercomprising indication indicia on said housing member and said annularring member to indicate the angular position of the object about saidaxis.
 8. The apparatus of claim 2 further comprising means forselectively locking said object in said predetermined angular positionwhen said application of rotary force to said ball screw assembly isdiscontinued.
 9. An indexable workholding apparatus comprising:alongitudinal column member having a first longitudinal axis, saidlongitudinal column member operably supporting at least one pair ofselectively movable jaw members for selectively clamping at least oneworkpiece therebetween, each said pair of selectively movable jawmembers being selectively movable along a corresponding secondlongitudinal axis that is substantially parallel to said firstlongitudinal axis; first and second upstanding support members forrotatably and axially supporting said longitudinal column therebetweenfor selective axial and rotational movement with respect to said firstlongitudinal axis; and an indexing assembly attached to said secondsupport member and communicating with said longitudinal column member,said indexing assembly having indexing means for selectively axiallydisplacing said column member along said first longitudinal axis to adisengaged position when a rotary force is initially applied thereto andpermitting said column member to thereafter be selectively rotated to apredetermined angular position about said first longitudinal axis uponthe further application of said rotary force to said indexing assemblyand selectively retaining said column member in said predeterminedangular position when said further application of rotary force isdiscontinued.
 10. The apparatus of claim 9 wherein said indexingassembly comprises:a first toothed ring non-rotatably attached to saidsecond support member; a second toothed ring axially and rotatablysupported by said second support member and arranged in confrontingrelationship with said first toothed ring for selective meshingengagement therewith, said second toothed ring being removably attachedto said longitudinal column member; and displacement means supported bysaid second support member, said displacement means communicating with asource of rotary force and selectively longitudinally displacing saidsecond toothed ring out of intermeshing engagement with said firsttoothed means in response to said initial application of rotary force,and permitting said second toothed ring to intermesh with said firsttoothed ring when said rotary force is discontinued.
 11. The apparatusof claim 10 wherein said displacement means further comprises:a ballscrew assembly axially supported by said second support member alongsaid first longitudinal axis for selectively axially displacing saidsecond toothed ring out of intermeshing engagement with said firsttoothed ring in response to said initial application of said rotaryforce; means for removably attaching said column to said ball screwassembly; and biasing means supported by said second support member forselectively biasing said second toothed ring into said intermeshingengagement with said first toothed ring when said rotary force isdiscontinued.
 12. The apparatus of claim 11 wherein said biasing meanscomprises a plurality of spring washers coaxially received on said ballscrew assembly for applying an axial force between said first and secondtoothed rings.
 13. The apparatus of claim 11 wherein said longitudinalcolumn has a longitudinal shaft member rotatably extending therethroughalong said first longitudinal axis and wherein said means for removablyattaching said longitudinal column to said ball screw assembly comprisesa first axial cavity in said ball screw assembly adapted tonon-rotatably receive therein an end of said longitudinal shaft member.14. The apparatus of claim 12 further comprising means for retainingsaid second toothed ring in said disengaged orientation after saidinitial application of rotary force and prior to the further applicationof said rotary force to said ball screw assembly.
 15. The apparatus ofclaim 14 wherein said means for retaining comprises:an axial annularcavity in said second support member; an annular ring member attached tothe perimeter of said second toothed ring and arranged for axial travelwithin said axial annular cavity in response to said axial displacementof said second toothed ring; and at least one wiper member attached tosaid second support member and extending into said axial annular cavityfor engagement with said annular ring member to create a frictionalforce therebetween to retain said second toothed ring in said disengagedorientation after said initial application of rotary force and prior tothe further application of said rotary force to said ball screwassembly.
 16. The apparatus of claim 15 further comprising indicationindicia on said second support member and said annular ring member toindicate the angular position of said longitudinal column member aboutsaid longitudinal axis.
 17. The apparatus of claim 10 further comprisingmeans for selectively locking said longitudinal column member in saidpredetermined angular position when said application of rotary force tosaid ball screw assembly member is discontinued.
 18. The apparatus ofclaim 9 wherein said first support member further comprises:at least onefirst attachment cavity therein adapted to receive a first fasteningmeans therein to removably attach and locate said first support memberon a surface; and at least one first enclosure member slidably attachedto said first support member and being selectively slidably displaceablebetween a first position wherein said first enclosure member encloses acorresponding said first attachment cavity and a second position whereinsaid corresponding said first attachment cavity is exposed to provideaccess to said first fastening means therein.
 19. The apparatus of claim18 wherein said second support member further comprises:at least onesecond attachment cavity therein adapted to receive a second fasteningmeans therein to removably attach and locate said second support memberon a surface; and at least one second enclosure member slidably attachedto said second support member and being selectively slidablydisplaceable between a primary position wherein said second enclosuremember encloses said corresponding second attachment cavity and asecondary position wherein said corresponding second attachment cavityis exposed to provide access to said second fastening means therein. 20.The apparatus of claim 9 wherein said column member has at least twolongitudinal surfaces, each longitudinal surface having a longitudinalcavity therein extending along a corresponding second longitudinal axisand a corresponding center jaw removably attached thereto andcorresponding first and second movable jaw-supporting members slidablysupported within each said second longitudinal cavity, said first andsecond movable jaw-supporting members having first and second extendedportions, respectively, which each extend out of the correspondingsecond longitudinal cavity for selective longitudinal movementtherealong toward and away from the corresponding center jaw and a firstjaw member corresponding to each said first extended portion and beingremovably attached thereto and a second jaw member corresponding to eachsaid second extended portion and being removably attached thereto. 21.An indexable workholding apparatus, comprising:a column member having afirst longitudinal axis and at least one longitudinal surfacesubstantially parallel to said first longitudinal axis, eachlongitudinal surface having a corresponding longitudinal cavity thereinand a corresponding center jaw removably attached thereto andcorresponding first and second movable support members slidablysupported within each said longitudinal cavity, said first and secondmovable support members having first and second extended portions,respectively, which each extend out of the corresponding longitudinalcavity for selective longitudinal movement therealong toward and awayfrom the corresponding center jaw and a first jaw member correspondingto each first extended portion and being removably attached thereto anda second jaw member corresponding to each second extended portion andbeing removably attached thereto; a shaft member rotatably attached tosaid longitudinal column and extending therethrough along saidlongitudinal axis; first and second support members rotatably andaxially supporting said shaft member therebetween such that said shaftmember and said longitudinal column member can be selectively axiallyand rotatably advanced about said longitudinal axis; and an indexingassembly comprising a first toothed ring non-rotatably attached to saidsecond support member and a second toothed ring axially and rotatablysupported by said second support member and arranged in confrontingrelationship with said first toothed ring for selective meshingengagement therewith, said second toothed ring removably attached tosaid longitudinal column member and displacement means supported by saidsecond support member and removably attached to said column member, saiddisplacement means selectively longitudinally displacing said secondtoothed ring out of intermeshing engagement with said first toothedmeans in response to said rotary force, and permitting said secondtoothed ring to intermesh with said first toothed ring when said rotaryforce is discontinued; and means for locking said longitudinal columnmember in said predetermined angular position when said application ofrotary force to said indexing assembly is discontinued.
 22. Theapparatus of claim 21, further comprising: indication indicia on saidsecond support member and said second toothed ring to indicate theangular orientation of said longitudinal column member about saidlongitudinal axis.
 23. The apparatus of claim 21 wherein said columnmember has a first longitudinal axis and four longitudinal surfaces eachsubstantially parallel to said first longitudinal axis, eachlongitudinal surface having a corresponding longitudinal cavity thereinand a corresponding center jaw removably attached thereto andcorresponding first and second movable support members slidablysupported within each said longitudinal cavity, said first and secondmovable support members having first and second extended portions,respectively, which each extend out of the corresponding longitudinalcavity for selective longitudinal movement therealong toward and awayfrom the corresponding center jaw and a first jaw member correspondingto each first extended portion and being removably attached thereto anda second jaw member corresponding to each second extended portion andbeing removably attached thereto.